In our school rubbish is separated. There are big boxes for all kinds of rubbish: 
glass, metal, paper, plastics and compost
In class we were talking about the importance of separating garbage and then decided to create big garbage-monsters to make separation more attractive. 

And that's how we did it:

We formed monsters out of screen wire
We cut out holes to throw in the rubbish (mouth, eyes, etc. )
We pasted our monsters with newspaper.
Finally we coloured the outside and decorated it with garbage we had collected in our sccolyard and classrooms before.